Keywords: scaffold, connection, second-order analysis, looseness, non-linear, stability function, semi-rigid.

As a result of the asymmetry of some of the connections scaffold joints often exhibit different behaviour under clockwise and anti-clockwise rotations and frequently have very low stiffnesses including the possibility of looseness at the connection. The looseness contributes to the overall deflection of the structure under loads [1]. These joints often deform plastically at low loads and hence elastic unloading curves are not parallel to the initial moment-rotation curves. The joints in scaffold structures are often subjected to frequent loading and unloading, for example due to wind pressure-wind suction effects.

This paper presents an algorithm to model scaffold behaviour and follow the full moment-rotation curve including nonlinear loading and unloading behaviour and including looseness. Different approximations to the moment-rotation curves are developed and applied to simple frames to determine their efficiency. Two bilinear approaches, the initial stiffness approach and a secant stiffness approach are shown to give poor results, the former over-estimating maximum performance, and the latter overestimating deflections whilst producing maximum loads which are very conservative. Finally the various models are applied to the frames including looseness effects where it is shown that for sway frames looseness reduces the capacity significantly but for braced frames looseness has less effect.

1

M.H.R Godley, R.G. Beale, "Analysis of large proprietary access scaffold structures", Proceedings of the Institution of Civil Engineer, Structures & Buildings, 146, 31-39, 2001. doi:10.1680/stbu.146.1.31.40542

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £140 +P&P)